In this paper, we use the notion of disparity instead of depth. Given the depth \(z_0\)  of the focal plane in Fig. REF , a depth \(z\)  can be directly converted into a disparity \(d\)  with \(d=\frac{z_0-z}{z}\)  (i.e. objects at depth \(z_0\)  from the camera plane have zero disparity). Refocusing the Light Field then consists in defining a new Light Field \(L^{\prime }(x,u)=L(x-us, u)\). The refocus parameter \(s\)  is defined such that the regions of disparity \(d=s\)  in the Light Field \(L\) , have a disparity equal to zero in the Light Field \(L^{\prime }\) . A refocused image, noted \(B^s\) , is then formed by refocusing the Light Field with parameter \(s\)  and integrating the light rays over the angular dimension as described in [1]}:
\(B^s(x) = \int _{\mathbb {R}} L(x-us,u) \psi (u) \mathrm {d}u.\) 
